Recent changes

Version 0.2.1

No longer rely on ActiveSupport. It was used for Array#sum and
Array#group_by, which are now implemented in ArrayExt.

Specs:

Parts of UrlHits and Entries got specs to help debugging the HitStats bug.

Added specs for all ArrayExt methods.

Version 0.2.0

Split single-file script into one file per existing class. Introduced new
classes to handle responsibilities that were not yet handled. Changed
classes involved in generating URL hits-based reports to be more flexible.
Generally refactored a lot of non-DRY code to be at least a bit nicer.